Tibiofemoral joint contact forces increase with load magnitude and walking speed but remain almost unchanged with different types of carried load

Abstract

Musculoskeletal injuries (MSI) in the military reduce soldier capability and impose substantial costs. Characterizing biomechanical surrogates of MSI during commonly performed military tasks (e.g., load carriage) is necessary for evaluating the effectiveness of possible interventions to reduce MSI risk. This study determined the effects of body-borne load distribution, load magnitude, and walking speed on tibiofemoral contact forces. Twenty-one Australian Army Reserve soldiers completed a treadmill walking protocol in an unloaded condition and wearing four armor types (standard-issue and three prototypes) with two load configurations (15 and 30 kg) for a total of 8 armor x load ensembles. In each ensemble, participants completed a 5-minute warm-up, and then walked for 10 minutes at both moderate (1.53 m⋅s-1) and fast (1.81 m⋅s-1) speeds. During treadmill walking, three-dimensional kinematics, ground reaction forces, and muscle activity from nine lower-limb muscles were collected in the final minute of each speed. These data were used as inputs into a neuromusculoskeletal model, which estimated medial, lateral and total tibiofemoral contact forces. Repeated measures analyses of variance revealed no differences for any variables between armor types, but peak medial compartment contact forces increased when progressing from moderate to fast walking and with increased load (p<0.001). Acute exposure to load carriage increased estimated tibiofemoral contact forces 10.1 and 19.9% with 15 and 30kg of carried load, respectively, compared to unloaded walking. These results suggest that soldiers carrying loads in excess of 15 kg for prolonged periods could be at greater risk of knee MSI than those with less exposure.

Military load carriage effects on the gait of military personnel: A systematic review

“…The added external mass due to the load will contribute to injury progression, since it requires gait alterations to minimise potential decrements to efficiency and performance (Baggaley et al, 2020;Liew et al, 2016;Orr et al, 2015a;Willy et al, 2019). However these alterations result in greater exposure to forces and joint loadings (Lenton et al, 2018), providing stresses to the legs and trunk that result in the increased risk of injury. It is important to understand the biomechanical responses to load carriage in soldiers in order to understand the injury aetiology and develop interventions and strategies to prevent these injuries occurring in the future.…”

Knee Load Distribution in Hip Osteoarthritis Patients After Total Hip Replacement

“…However, for the knee CF less information is available, especially when considering MKCF and LKCF. Lenton et al (2018) published on the effect of speed on medial and total tibiofemoral CF, whereas no effect on the lateral CF was found. However, the walking speeds were much higher (1.53 and 1.81 ms −1 ) so it must be questioned if the results can be transferred to the slower walking speed of patients, as measured in the present study.…”

Neuromusculoskeletal Modeling-Based Prostheses for Recovery After Spinal Cord Injury

“…The skeletal system is defined by multiple segments (i.e., bones) connected by three-dimensional joints mobilized accordingly to their anatomical function (Seth et al, 2018). EMG-informed NMS models have been used to successfully estimate muscle forces, joint contact forces, and joint stiffness in the lower and upper limbs of individuals with a variety of neuromuscular conditions (Sartori et al, 2015; Konrath et al, 2017; Hall et al, 2018; Hoang et al, 2018, 2019; Lenton et al, 2018; Kian et al, 2019). NMS models are the optimal platform for integration of multiple assistive devices, enabling physics-based sensor fusion, where input and output quantities are mechanistically and causally related.…”